Field of Invention
This invention relates generally to endoscopic instrumentation, and more particularly to an articulated optical arm adapted to optically link an endoscopic telescope to a viewing station through an image-erecting optical barrel which is rotatable by a remotely-controlled barrel rotator whereby the image being viewed may be properly oriented.
An endoscope is an instrument for visualizing the interior of a hollow organ such as the rectum or urethra. A typical modern endoscope for surgical procedures includes a tubular cannula that is insertable into a body cavity, the cannula incorporating imaging means leading to a telescope, making it possible to directly view the region of interest through the eyepiece of the telescope.
The endoscopic telescope is provided with an adapter to which is attachable a flexible fiber optic cable coupled to a light source, thereby illuminating the region being observed. Also, a raceway or other means to accommodate scalpels, forceps and other surgical tools expressly designed to function within a stainless steel tube forming the external sheath of the endoscope can be included.
Normally, when observing an internal site through the endoscopic telescope, the viewer brings his eye close to the eyepiece. But when performing surgery, one cannot look into the eyepiece without having the face of the viewer interfere with the fingers manipulating the surgical instrument, for the instrument handles are in the proximity of the eyepiece.
One function of an articulated optical arm is to make it possible for a surgeon to view an internal organ through an endoscopic telescope from a viewing station well separated from the telescope, so that the surgeon is able, without difficulty, to manipulate the surgical instruments associated with the endoscope. Typical of commercially-available articulated optical arms is the model 29023 device manufactured by Karl Storz Gmbh & Co. of West Germany. This device fits all endoscopic telescopes and serves to optically link the telescope to a film or video camera while permitting simultaneous observation by the operator and an observer.
An articulated optical arm is composed of a series of arm sections which are mechanically interhinged and optically intercoupled by special joints. Each section houses a solid quartz rod to transmit the image, and each joint includes a pair of optically-coupled prisms to transfer the image from one arm section to the next, regardless of the relative angular positions thereof.
The first section in the series is coupled to the endoscopic telescope; and by adjusting the sections of the articulated arm relative to each other, one can extend, retract or otherwise shift the position of the endoscope in the body cavity while maintaining an uninterrupted optical link between the endoscope and the viewing station. However, as such adjustments are made, the relative orientation of the image transfer prisms in each joint is altered, with a consequent rotation of the image about the optical axis.
It is for this reason that the last in the series of sections is coupled to the terminal eyepiece of the articulated arm through a rotatable barrel which houses an image-erecting prism. By manually rotating this barrel clockwise or counterclockwise, the observer is able to restore the image to its proper orientation, regardless of the degree and direction of image displacement resulting from a given arm adjustment.
When the terminal eyepiece of the articulated arm is coupled to the video camera of a TV monitor, a surgeon is then able to advantageously view the surgical site as a magnified illuminated display on a TV screen rather than through the limited confines of an eyepiece. The articulated arm may include at its terminal, a beam splitter which divides the image between a lens coupling the arm to a video camera (or a recording motion picture camera) and an auxiliary eyepiece, so that one may simultaneously observe and record the surgical site in the course of an endoscopic procedure.
The term "viewing station" as used herein encompasses whatever arrangement is provided in conjunction with the terminal eyepiece of the articulated arm to examine and/or record the body region visualized through the endoscope associated with the arm.
The problem to which the present invention is addressed is the practical difficulty experienced by an operating surgeon with conventional articulated arms during an endoscopic procedure. The surgeon's hands are engaged in manipulating the surgical instruments, yet he is also called upon from time to time to shift the position of the endoscope so that he can properly view various aspects of the region in which he is operating. In making these shifts, the articulated arm is adjusted accordingly. But with each new adjustment of the articulated arm, the image transmitted through the arm undergoes circumferential displacement about the optical axis in a direction and to a degree that depends on the nature of the adjustment.
It becomes necessary, therefore, with each adjustment which may occur with a fair degree of frequency in the course of the procedure, for the surgeon to rotate the barrel in order to re-erect the image presented at the viewing station. But the surgeon has only two hands, and if these are occupied in manipulating the instruments, he may either have to interrupt the procedure to turn the barrel, or he may be forced to make an accommodation to the displaced image.
Thus if at a critical juncture, the surgeon is faced with an upside-down image of the internal region being operated on, and he is then not in a position to rotate the image-erecting barrel, he must then take the inverted image into account when manipulating his instruments. This gives rise to serious eye-to-hand or psychomotor coordination difficulties and may further complicate an already complicated procedure.
Another factor which comes into play is the maintenance of sterility. Surgical instruments must be cleaned and sterilized prior to use, and the surgeon takes steps before a procedure to disinfect his hands and to put on sterile gloves. But articulated optical arms cannot be disinfected or sterilized; hence if the surgeon manipulates the image-erecting barrel with his hands, he may thereby violate the field of sterility.